The gaskets on the body connects that the ball or pin lock fittings slide over. 7/16" ID with a 3/32" cross section. Made of FDA BUNA-N rubber.We also use this as a replacement for the smaller compression ring in our 1/2" Compression fittings so that you can create a snug fit in a Sanke keg conversion kit without permanently compressing a ring on the pick up tube.